Tailoring intermediate switching states in magnetic La0.67Sr0.33MnO3 multilayers

Intermediate switching states are of great interest for developing advanced magnetic memories. In this paper, the magnetic switching process is studied in the multilayers that are fabricated using two distinct ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ building blocks, i.e., ${\mathrm{PbTiO}}_3$/${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$/${\mathrm{NdGaO}}_3$ (block A) and ${\mathrm{PbTiO}}_3$/${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$/${\mathrm{PbTiO}}_3$ (block B) with different intralayer ferromagnetic couplings. Accordingly, the multilayer that consists of two types of ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ blocks is featured by two distinct Curie temperatures and coercive fields, as expected. On the other hand, the sample only composed of block B displays a single Curie temperature but two unexpected coercive fields. While the single Curie temperature indicates the same intralayer ferromagnetic coupling in all ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ sublayers, two coercive fields suggest the existence of an intermediate switching state. The detailed study on polarized neutron reflectometry reveals that this intermediate state exhibits a gradual change of magnetization, from parallel to antiparallel with respect to the external magnetic field, across ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ sublayers approaching the substrate. The competition between the interlayer exchange and magnetostatic interaction is highlighted to show the intermediate magnetization structure of ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ multilayers with identical intralayer coupling. Our findings shed light on controlling switching states and may contribute to the design of nanoscale high-density magnetic memories.